Estes Leviathan (Over) Build

I am currently (overbuilding) an Estes Leviathan. This is my first MPR, and I hope to push it into HPR status with some of the smaller L1 29mm engines. My plan is to use this rocket to get the L1 certification and some experience, and then move to a larger, true HPR.

After reading some cool posts on this forum (think qquake2k and his build photos and http://www.rocketryforum.com/showthr...ries-II-baffle) I decided to go zipperless with an S-type baffle. My only problem is now I need to make sure the center of gravity hasn't shifted to much. I made the baffle parts out of bass wood. I cut out six circles, and glued together two at a time, for a total of three circles. I cut one in half for the half moons in the baffle. The other two got an eyebolt, nut, and washer epoxied in place. One received some holes, the other is solid. I am putting them in the tube coupler that goes just ahead of the motor mount. Again, JB weld and Steel epoxy clay. Pics...

Here are the fins going on. Only JB weld here. I put JB weld on the underside of the fins and push them into place. Some are pretty tight going in. Then I apply a liberal amount of JB weld for an external fillet. This was slow going given the 4+ hour cure time for the epoxy.
Right now I am waiting for the fourth fin to set. More to come.

I am currently (overbuilding) an Estes Leviathan. This is my first MPR, and I hope to push it into HPR status with some of the smaller L1 29mm engines. My plan is to use this rocket to get the L1 certification and some experience, and then move to a larger, true HPR.

I don't understand why you are using JB Weld throughout. I can see where heat might be an issue, but regular hobby epoxy should work fine or even wood glue. Another option is epoxy clay. After it dries to can file and sand it to shape the fillets. Just putting in my two cents. Good luck

... My only problem is now I need to make sure the center of gravity hasn't shifted to much. ...

It's always good to check! Rocksim sez the CP is ~40" from the nose, just behind where the fins meet the body. You have some margin to play with since it shows the Ventris has a 2.8x margin with a G80 loaded.

Just a warning, those Estes thick-wall tubes are a weeee bit too thin to really put any high-thrust motors in there. Aka your giant fillets are only getting you so far.
I put my Partizon together with wood glue, and it held up to an H133 happily. Better safe than sorry though I guess. I also foamed in my fin can and epoxy-clayed some fillets on my fins.

Nice job with the baffle. I really have to start putting these into my rockets... Wadding is a pain.

Oh, and another note... Get a bigger chute. With all that weight, a 24" will drop you a little quicker than you'd like.

I built mine nearly stock with wood glue. I have no worries about putting a H410 in it. A slightly smaller rocket with surface mounted basswood fins survived one just fine only to drift away never to be found.

I built mine nearly stock with wood glue. I have no worries about putting a H410 in it. A slightly smaller rocket with surface mounted basswood fins survived one just fine only to drift away never to be found.

Now,that would be an interesting flight. Please post a video if you try it. The down side of any H will be the probability of loss.

Just FYI, If you would have built with wood glue it would be stronger then your current um... situation and a TON lighter too.
You say this is your first MPR and you will be getting your L1 with this. Why skip MPR? IMHO everyone should spend some time in MPR to play with high power style construction techniques before going to HPR. That's what i did and I'm glad that I made that decision.
Take a look at the "what adhesive should I use" article in my blog in the sig. below. It'll explain a lot about what adhesives are best in certain situations. You'll save a lot of weight by using the correct adhesives.

Just FYI, If you would have built with wood glue it would be stronger then your current um... situation and a TON lighter too.
You say this is your first MPR and you will be getting your L1 with this. Why skip MPR? IMHO everyone should spend some time in MPR to play with high power style construction techniques before going to HPR. That's what i did and I'm glad that I made that decision.
Take a look at the "what adhesive should I use" article in my blog in the sig. below. It'll explain a lot about what adhesives are best in certain situations. You'll save a lot of weight by using the correct adhesives.

Alex

I agree with Alex. There really isn't a rush to jump up levels. It's a hobby have fun and enjoy and give your wallet a break from the high power stuff.

Learn by doing

I have learned a lot from this forum... and a lot by doing stuff myself. Years ago, my first 3" rocket was put together with epoxy and did fine on 29mm H motors. I really learned lots about good building techniques /light weight / and strength by DOING/building/ making mistakes.

I built and destroyed several BT80 Super Big Bertha's - and in the process -NOW - I know...

- to sand or scuff up areas where I'm going to glue. (makes the joint super strong) (they don't always tell you that in the instructions)
- how to properly make a double glue joint. (the material will fail before the glue joint)
- how to plan ahead and change or improve a few things (elastic... get real )
- Most rockets will fly higher and go faster on H and I motors (L1) when the rocket is paper/wood and wood glue.

Not sayin epoxy, 'glas, and carbon don't have their place. Sometimes exotic materials are the only/best way to go.

My Leviathan (mid break zipperless) was built with Elmers Wood glue Max**, and I'm positive it will do fine on the largest 4 or 5 grain 29mm motor that will fit..

This is a learning experience for me. I am glad that I am not learning on a $100+ HP rocket. I am thinking a second Estes Pro Series is in my near future.

I felt the same about mine. I L1'ed for under 100 bucks... Motor and all. If you live near a Hobby Lobby, use the 40% off coupon to get your next one. Mine cost me 30 bucks!

Don't get us all wrong, I think I speak for everyone in saying that this will definitely fly L1 motors, possibly higher. Just don't be so quick to put a nice, small, F26 in there or something. Even worse, stay away from wicked high thrusts... And yes, its all about the learning. Just look at my signature! It's my belief that the only way to really get good at a technique is to do it wrong a bunch.

FYI, Estes has a Nike Smoke Pro-Series kit on the "Coming soon" part of their site.

I got the baffle glued into the fin can assembly. The JB weld makes a nice fillet. I used 5-min Gorilla Glue Epoxy for the fin can. It is less viscous, and should hopefully bond well paper-to-paper.

Total weight of the fin can with baffle, as pictured, is 12.5 oz.

I also got the forward bulkhead glued in place. I put it 5 inches into the top of the body tube. That will allow me to glue in some weight if needed and still have plenty of room to get the nose cone on. Used Gorilla wood glue for the top bond. Once that is set I will use either gorilla wood or gorilla white (foaming) to do the inside fillet.

Well, since I was planning on using HP engines (albeit smaller ones) I didn't worry to much about the weight. I didn't really want to set an altitude record, given that you have to recover the rocket for L1 cert.

The weight of all the kit parts and an Estes G80-7T motor is 1 pound 12 ounces. That will go up a little when I add a 3-grain CTI case and hardware, a little bigger parachute, and the glue needed to stick the rest of the rocket together. I might need some weight in the nose if the center of gravity moved to far aft.

If you want to be able to get to your "payload bay" (I'm assuming that's why you put in a foward bulkhead), I recommend using some of the little plastic rivets. You can get them at home depot. That way, you can get to your bay easily, but the nosecone will always stay on.

If you're adding weight to the rocket, put it in the nosecone! It's a much better place to add it. Use some airgun BB's to get the weight you want, then fill the volume they take up in epoxy.

Very interesting build. And I thought I overbuilt my rockets! I use two-part 5 minute epoxy almost exclusively in all my builds, from LPR to MPR. I've flown up to I's, and never had the epoxy fail. While JB Weld has its place, I rarely use it because of the thick viscosity and slow cure time. I prefer two-part epoxy because it doesn't "grab" like wood glue can, when inserting motor mounts and couplers into body tubes. I also like how I can choose different cure times for different projects (5, 15, 30 minute, etc.). And it doesn't run as easily as wood or white glues. Having said that, though, I know some swear by wood glue, and I'm a firm believer in its strength. When applied properly, the joint will be stronger than the materials. Experiment, and use what works best for you. FYI, for external fillets, I'm a big believer in Titebond molding glue. It doesn't run.